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RN: Show Warning for Background Remote Debuggers

Summary:
Some recent change to Chrome causes the remote debugger to be throttled unexpectedly if it is in a background tab. Although this does not fix the problem, it raises the issue and suggests a workaround.

I also cleaned up some littering of the global namespace in the debugger web worker.

Reviewed By: jingc

Differential Revision: D4104515

fbshipit-source-id: 56e46c0e759bec4c42d3baedd4d2d46cdea2e4a0
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yungsters authored and Facebook Github Bot committed Oct 31, 2016
1 parent 448e66b commit 8b653cde56c132e3f32a6dd4a79ac7be65b121cd
Showing with 74 additions and 32 deletions.
  1. +14 −0 local-cli/server/util/debugger.html
  2. +60 −32 local-cli/server/util/debuggerWorker.js
@@ -48,6 +48,7 @@
return 'If you reload this page, it is going to break the debugging session. ' +
'You should press' + refresh_shortcut + 'in simulator to reload.';
};
updateVisibility();
}
function shutdownJSRuntime() {
@@ -58,6 +59,15 @@
}
}
function updateVisibility() {
if (worker) {
worker.postMessage({
method: 'setDebuggerVisibility',
visibilityState: document.visibilityState,
});
}
}
ws.onopen = function() {
setStatus(INITIAL_MESSAGE);
};
@@ -103,6 +113,10 @@
}
setTimeout(connectToDebuggerProxy, 500);
};
// Let debuggerWorker.js know when we're not visible so that we can warn about
// poor performance when using remote debugging.
document.addEventListener('visibilitychange', updateVisibility, false);
}
connectToDebuggerProxy();
@@ -6,45 +6,73 @@
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
/* global __fbBatchedBridge, self, importScripts, postMessage, onmessage: true */
/* eslint no-unused-vars: 0 */
'use strict';
var messageHandlers = {
'executeApplicationScript': function(message, sendReply) {
for (var key in message.inject) {
self[key] = JSON.parse(message.inject[key]);
}
var error;
try {
importScripts(message.url);
} catch (err) {
error = JSON.stringify(err);
onmessage = (function() {
var visibilityState;
var showVisibilityWarning = (function() {
var hasWarned = false;
return function() {
// Wait until `YellowBox` gets initialized before displaying the warning.
if (hasWarned || console.warn.toString().includes('[native code]')) {
return;
}
hasWarned = true;
console.warn(
'Remote debugger is in a background tab which may cause apps to ' +
'perform slowly. Fix this by foregrounding the tab (or opening it in ' +
'a separate window).'
);
};
})();
var messageHandlers = {
'executeApplicationScript': function(message, sendReply) {
for (var key in message.inject) {
self[key] = JSON.parse(message.inject[key]);
}
var error;
try {
importScripts(message.url);
} catch (err) {
error = JSON.stringify(err);
}
sendReply(null /* result */, error);
},
'setDebuggerVisibility': function(message) {
visibilityState = message.visibilityState;
},
};
return function(message) {
if (visibilityState === 'hidden') {
showVisibilityWarning();
}
sendReply(null /* result */, error);
}
};
onmessage = function(message) {
var object = message.data;
var object = message.data;
var sendReply = function(result, error) {
postMessage({replyID: object.id, result: result, error: error});
};
var sendReply = function(result, error) {
postMessage({replyID: object.id, result: result, error: error});
};
var handler = messageHandlers[object.method];
if (handler) {
// Special cased handlers
handler(object, sendReply);
} else {
// Other methods get called on the bridge
var returnValue = [[], [], [], 0];
try {
if (typeof __fbBatchedBridge === 'object') {
returnValue = __fbBatchedBridge[object.method].apply(null, object.arguments);
var handler = messageHandlers[object.method];
if (handler) {
// Special cased handlers
handler(object, sendReply);
} else {
// Other methods get called on the bridge
var returnValue = [[], [], [], 0];
try {
if (typeof __fbBatchedBridge === 'object') {
returnValue = __fbBatchedBridge[object.method].apply(null, object.arguments);
}
} finally {
sendReply(JSON.stringify(returnValue));
}
} finally {
sendReply(JSON.stringify(returnValue));
}
}
};
};
})();

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